Drive mechanism of a drug delivery device comprising an accessory drive

ABSTRACT

A drive mechanism of a drug delivery device and a respective drug delivery device for setting and dispensing of a dose of a medicament are presented, where the drive mechanism has an elongated housing extending in an axial direction, a piston rod to operably engage with a piston of a cartridge containing the medicament, a dosing arrangement manually and axially displaceable relative to the housing for setting and dispensing of the dose, and an accessory drive operably engaged with the piston rod to support a manually operated dose dispensing displacement of the dosing arrangement.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a U.S. National Phase Application pursuant to35 U.S.C. § 371 of International Application No. PCT/EP2014/050544 filedJan. 14, 2014, which claims priority to European Patent Application No.13151199.0 filed Jan. 14, 2013. The entire disclosure contents of theseapplications are herewith incorporated by reference into the presentapplication.

TECHNICAL FIELD

The present invention relates to a drive mechanism of a drug deliverydevice to dispense and/or to inject a predefined dose of a medicamentfrom a cartridge. The drug delivery device is generally manuallyoperable and allows for individually setting and/or dispensing of a doseof the medicament.

BACKGROUND

User operated drug delivery devices are as such known in the art. Theyare typically applicable in circumstances, in which persons withoutformal medical training, i.e., patients, need to administer an accurateand predefined dose of a medicament, such as heparin or insulin. Inparticular, such devices have application, where a medicament isadministered on a regular or irregular basis over a short-term orlong-term period.

In order to accommodate with these demands, such devices have to fulfila number of requirements. First of all, the device must be robust inconstruction, yet easy to use in terms of handling and in understandingby the user of its operation and the delivery of the required dose ormedicament. The dose setting must be easy and unambiguous. Where thedevice is to be disposable rather than reusable, the device should beinexpensive to manufacture and easy to dispose.

Some mechanically implemented drug delivery devices, e.g. pen-typeinjectors, comprise a dosing or dose setting arrangement featuring adose setting member to be displaced in axial proximal direction forsetting of a dose. For dispensing of a respective dose, the proximallyextended dose setting member may then have to be manually depressed indistal direction, e.g. to advance a piston of the cartridge in distaldirection. Here, a user may have to exert a comparatively largedispensing force, which may pose a burden to physically impaired personsor patients.

Apart from manually or purely mechanically operated drug deliverydevices there also exist electro-mechanical drug delivery deviceswherein at least dose setting, dose selection or administration of anappropriate dose of the medicament is controlled by way of electroniccircuitry, for example a controller, a microprocessor, and/or the like.Such electronic or electro-mechanical devices provide a high dosingaccuracy and may support long-term monitoring of doses dispensed by thedevice. Hence, a dosing and dispensing scheme can even be stored in thedevice allowing to recall the dose dispensing history later on.

However, with electronic or electro-mechanical devices, setting anddispensing of a dose might be less intuitive compared to anall-mechanically implemented device. In particular, with a mechanicallyimplemented device, the user has to apply a certain injection force,thereby obtaining a force feedback. By introducing an electro-mechanicaldevice to the patient and replacing an all-mechanical device, thepatient or user may be confronted with an unfamiliar or inconvenientoperation scheme. Hence, there may emerge a certain danger of misuse andsuboptimal medical treatment. Also, the acceptance of such anelectro-mechanical device by the user may be rather low.

With an electronic or electromechanical drug delivery device not onlythe dose setting and dose dispensing process is electricallyimplemented. Also a dose indicator, typically in form of a display tovisually illustrate the size of a dose to the user may be implementedall electronically. However, in the event that the drug delivery deviceor one of its electronic components becomes subject to failure, theremay be a certain danger, that the dose is incorrectly or incompletelyindicated to the user of the device. It may then occur that theindicated or illustrated dose size does not match with the size of adose actually set or dispensed by the drug delivery device.

It is therefore an object of the present invention to provide animproved drive mechanism for a drug delivery device, in particular for apen-type injector. The drive mechanism should be mechanically operableand should provide direct and intuitive feedback to the user during dosedispensing. The drive mechanism should further come along with asubstantially reduced dispensing force required to be exerted by theuser for dose injecting or dose dispensing. In that sense the drivemechanism should provide a rather easy and intuitive handling, both forsetting as well as for dispensing of a dose. Moreover, the inventionalso relates to a drug delivery device comprising such improved drivemechanism.

SUMMARY

In a first aspect a drive mechanism of a drug delivery device isprovided. The drive mechanism is operable for setting as well as fordispensing of a dose of a medicament. The drive mechanism comprises anelongated housing extending in an axial direction. The drive mechanismfurther comprises a piston rod to operably engage with a piston of acartridge, wherein the cartridge contains the medicament to be dispensedby the drive mechanism and/or by the drug delivery device, respectively.

Typically, the cartridge comprises a piston slidably disposed therein inaxial direction that serves as a proximal seal of the cartridge's bodyor barrel. The drive mechanism is particularly operable to apply or toexert distally-directed thrust to the piston of the cartridge in orderto expel a required dose of the medicament via a distally located septumof the cartridge, which is to be penetrated by a piercing element, suchlike an injection needle.

The drive mechanism further comprises a dosing arrangement manually andaxially displaceable relative to the housing for setting and fordispensing of the dose. By means of the dosing arrangement, a size of adose to be dispensed by the device can be individually set by the userduring a dose setting procedure. In a subsequent step and after settingof a predefined dose, the user may then trigger or conduct an injectionprocedure by way of manually applying an injection force in distaldirection to the dosing arrangement, in particular to a dose dispensingmember, which may be connected with or may be implemented in the dosingarrangement.

Here the dosing arrangement may allow and support setting of doses ofvariable size. Alternatively, the dosing arrangement may be configuredto dispense a fixed dose, which is not to be modified by the user.

The drive mechanism further comprises an accessory or auxiliary driveoperably engaged with the piston rod of the drive mechanism to supportthe manually operated dose dispensing displacement of the dosingarrangement. By means of the accessory drive, the dispensing procedurecan be supported. The accessory drive typically provides an additionalforce or torque by way of which a manually operable dose dispensingaction can be supported. Consequently, the minimum dispensing force tobe provided and to be exerted by a user can be effectively reduced. Thegeneral handling of the drive mechanism and of a respective drugdelivery device can therefore be enhanced and facilitated.

The accessory or auxiliary drive is particularly adapted to exclusivelysupport the dispensing action of the drive mechanism. During dosesetting, the accessory drive may be effectively inoperable. Moreover,the accessory drive is operable to exclusively support but not toentirely control a dispensing procedure of the drive mechanism. In thisway, the mechanical interaction between the dosing arrangement and thepiston rod can remain substantially unmodified compared to an allmechanical implementation of a drive mechanism.

Typically, the dosing arrangement is subject to an axially-directeddisplacement relative to the housing during dose setting as well asduring dose dispensing. Since the dosing arrangement and the piston rodremain operably and mechanically engaged, overall handling of the dosingarrangement for setting and/or dispensing of a dose may stronglyresemble a general handling of an all mechanically implemented drivemechanism, to which a user or patient may already be used to.

Moreover, through the mechanical and operable engagement of dosingarrangement and piston rod the drive mechanism provides an allmechanical indication and control about the size of the dose actuallyset and/or dispensed. In the event, that the accessory drive should runout of power or in the event, that the accessory drive or componentsthereof become subject to malfunction, the drive mechanism remains fullyoperational. A malfunction of the accessory drive may then only affectthe operational comfort of the drive mechanism and hence of the drugdelivery device.

In another embodiment, the accessory drive is power operated. Here, theaccessory drive is electrically driven. The accessory drive maytherefore comprise a DC motor electrically connected to a battery, e.g.a rechargeable battery. Typically, the accessory drive is selectivelyoperable on demand during a dose dispensing procedure. The accessorydrive is activated at the beginning of a dispensing procedure andremains activated until the dispensing procedure ends.

The accessory drive typically provides a predefined torque of constantor variable magnitude which is to be transferred to at least onefunctional component of the drive mechanism to transfer the supplementaltorque or driving force to the piston rod thereof. Mutual coupling ofthe accessory drive and the piston rod may either be permanent ortemporal. Additionally, the mutual coupling of accessory drive andpiston rod may comprise a clutch or a clutch mechanism, which isoperable during dose dispensing to couple the accessory drive and thepiston rod.

The mutual coupling of accessory drive and piston rod may comprise adirect mechanical interaction of the accessory drive with a rotatablysupported piston rod. However, in the event, that the piston rod isrotatably locked to the housing and is to be slidingly displacedrelative to the housing for dispensing of a dose, the accessory drivemay be mechanically engaged with another functional component of thedrive mechanism, e.g. with a drive sleeve or the like, which is eitherdirectly or indirectly engaged with the piston rod for driving the samein distal, hence in dose dispensing direction.

In a further embodiment the dosing arrangement comprises a dose settingmember, a dose indicating member and a dose dispensing member. Thedosing arrangement therefore represents and corresponds to a unitaxially displaceably supported relative to the housing for settingand/or dispensing of a dose. In typical embodiments, the dose indicatingmember comprises a sleeve having various dose size indicating numbersprinted thereon. The dose indicating member is displaceable in proximaldirection relative to the housing during a dose setting procedure,thereby exhibiting a series of dose indicating numbers at its outercircumference.

Typically, such numbers show up in a dose indicating window of thehousing. Furthermore, it is conceivable, that the housing comprises anindicator at its proximal end to visualize the size of a dose actuallyset by the drive mechanism.

The dose indicating member may comprise a dose setting member, e.g. atits proximal end. The dose setting member typically comprise a dose dialgrip providing a well defined gripping and rotating of the dose settingmember and the interconnected dose indicating member during a screw-likedose setting displacement of the entire dosing arrangement. At itsproximal end face, the dosing arrangement may further comprise the dosedispensing member.

The dose dispensing member typically comprises a dose button to bedepressed in distal direction for dispensing of a dose previously setduring the dose setting procedure. Here, the dose dispensing member mayalso comprise a thrust-receiving structure to receive and to transferdistally-directed thrust exerted by a user's thumb during a dosedispensing procedure.

For switching the device from a dose setting mode into a dose dispensingmode, the dose dispensing member or the entire dosing arrangement may bedisplaceably supported in axial, typically in distal direction toactivate or to deactivate a clutch mechanism of the drive mechanism. Byactivating or deactivating the clutch mechanism, the drive mechanism canbe switched between a dispensing and a dose setting mode.

In a further embodiment, the accessory drive is operably engageable withthe dose setting member or with the dose indicating member during a dosedispensing procedure for dispensing of the dose previously set. In thiscontext an operable engagement between two or more components relates toa mechanical engagement for transferring a torque or a force effectbetween said components.

When mechanically and directly coupled to either the dose setting memberor to the dose indicating member, a dispensing force provided by theaccessory drive will be transferred via the dose setting member or viathe dose indicating member to the piston rod.

Otherwise, the accessory drive may be directly coupled or engaged withthe piston rod. Then, during a dispensing procedure supported by theaccessory drive, the return motion of the dose setting member and/or ofthe dose indicating member may be governed and induced by the piston rodand/or by the user supported displacement of dose setting member.

In another embodiment, the dosing arrangement is axially displaceable inproximal direction relative to the housing for setting of the dose.Correspondingly, the dosing arrangement, hence the dose indicatingmember, the dose setting member as well as the dose dispensing memberare displaceable in distal direction for dispensing of the dose. Thisway, the device may return into an initial configuration at the end of adispensing procedure.

In another embodiment, the dose indicating member is operably, hencemechanically engaged with the piston rod during the dose dispensingprocedure. In such an embodiment, the accessory drive may act on thedose indicating member and may be therefore operably and directlyengaged with the dose indicating member. In this embodiment, activationof the accessory drive leads to a combined and supported displacement ofthe dose indicating member and of the piston rod during the dosedispensing procedure. Torque or forces provided by the accessory drivemay then be transferred to the piston rod via the dose indicatingmember.

In this way, the dose metering and dose indicating can be implementedall-mechanically. A failure or malfunction of the software or electronichardware of the drive mechanism has then no substantial effect on thedose metering and dose indication. As a consequence, the failure safetyof the drive mechanism can be improved. As a further benefit, respectivesoftware and electronic hardware of the drive mechanism can be designedand implemented in a more simple and cost-efficient way.

In another embodiment, the dose dispensing member is operably, hencemechanically engaged with the piston rod during dose dispensing. In thisway a manually applied and distally exerted dispensing force can bedirectly transferred to the piston rod for driving the same in distaldirection. The combined and simultaneous displacement of the dosedispensing member and the piston rod can be supported by means of theaccessory drive. For driving the piston rod in distal and dosedispensing direction during a dispensing procedure it may be sufficientwhen the accessory drive is operably or mechanically engaged with thedose dispensing member. A torque or force provided by the accessorydrive can be transferred to the piston rod via the dose dispensingmember, accordingly.

In another embodiment, the accessory drive is coupled with a switch toselectively activate and/or to deactivate the accessory drive. Theswitch may be inherently or automatically activated or deactivated atthe beginning and/or at the end of a dose dispensing procedure,respectively. The switch may be particularly operable to start and tostop the accessory drive.

In a further embodiment, the switch is operably engaged with the dosedispensing member. In particular, the switch may be integrated into thedose dispensing member. In this way, depression of the dose dispensingmember for dispensing of the dose may inherently and simultaneouslydepress the switch, thereby simultaneously activating the accessorydrive.

In a further embodiment the switch is located in an interface betweenthe dose dispensing member and the dose setting member. The switch maybe implemented all-mechanically and may comprise a first portion fixedto the dispensing member and may further comprise a second portion fixedto the dose setting member. In this embodiment, the dose dispensingmember is displaceable relative to the dose setting member, at least fordispensing of a dose. Relative displacement of the dose dispensingmember with regard to the dose setting member may then lead to anelectrical connecting or disconnecting of first and second portions ofthe switch, respectively.

According to another embodiment, the switch is actuatable against arestoring force. Typically, the switch is operable against the action ofa restoring element, such like a spring element. Accordingly, depressingof the switch may take place against the action of the spring, such thata release of the switch automatically transfers the switch into itsinitial position under the action of the spring.

In a further embodiment, the drive mechanism comprises a control toregulate the power of the accessory drive in dependence of a dispensingforce applied or exerted by a user of the drive. Here, the switch isoperable to quantitatively determine the size or magnitude of adispensing force acting thereon in distal direction during dosedispensing. By measuring or determining the magnitude of the externallyapplied force, the power of the accessory drive can be modifiedaccordingly.

In the event that a user applies a comparatively large dispensing forceto the dose dispensing member, the support of the accessory drive duringa dose dispensing procedure may be comparatively small. In this case,electrical energy can be saved to a certain degree. In another event,wherein the actuation force provided by a user is comparatively low, thetorque or force provided by the accessory drive may be raisedaccordingly.

In effect, the power and force or torque to be provided by the accessorydrive can be individually adapted to the dispensing force exerted by auser and be actually present on the dose dispensing member. Themagnitude of the power, force or torque provided by the accessory driveduring dose dispensing can be regulated in such a way, that the sum ofthe forces applied by a user and the forces or torque provided by theaccessory drive at least exceeds a predefined threshold force requiredto drive or to advance the piston rod in distal direction.

In another aspect the invention furthermore relates to a drug deliverydevice and in particular to a pen-type injector. The drug deliverydevice comprises a drive mechanism as described above and furthercomprises a cartridge at least partially filled with a medicament andbeing sealed by a piston in proximal direction, wherein the piston is tobe displaced in distal direction by the piston rod of the drivemechanism for expelling and for dispensing of a dose of the medicament.

The term “drug” or “medicament”, as used herein, means a pharmaceuticalformulation containing at least one pharmaceutically active compound,

wherein in one embodiment the pharmaceutically active compound has amolecular weight up to 1500 Da and/or is a peptide, a protein, apolysaccharide, a vaccine, a DNA, a RNA, an enzyme, an antibody or afragment thereof, a hormone or an oligonucleotide, or a mixture of theabove-mentioned pharmaceutically active compound,

wherein in a further embodiment the pharmaceutically active compound isuseful for the treatment and/or prophylaxis of diabetes mellitus orcomplications associated with diabetes mellitus such as diabeticretinopathy, thromboembolism disorders such as deep vein or pulmonarythromboembolism, acute coronary syndrome (ACS), angina, myocardialinfarction, cancer, macular degeneration, inflammation, hay fever,atherosclerosis and/or rheumatoid arthritis,

wherein in a further embodiment the pharmaceutically active compoundcomprises at least one peptide for the treatment and/or prophylaxis ofdiabetes mellitus or complications associated with diabetes mellitussuch as diabetic retinopathy,

wherein in a further embodiment the pharmaceutically active compoundcomprises at least one human insulin or a human insulin analogue orderivative, glucagon-like peptide (GLP-1) or an analogue or derivativethereof, or exendin-3 or exendin-4 or an analogue or derivative ofexendin-3 or exendin-4.

Insulin analogues are for example Gly(A21), Arg(B31), Arg(B32) humaninsulin; Lys(B3), Glu(B29) human insulin; Lys(B28), Pro(B29) humaninsulin; Asp(B28) human insulin; human insulin, wherein proline inposition B28 is replaced by Asp, Lys, Leu, Val or Ala and wherein inposition B29 Lys may be replaced by Pro; Ala(B26) human insulin;Des(B28-B30) human insulin; Des(B27) human insulin and Des(B30) humaninsulin.

Insulin derivates are for example B29-N-myristoyl-des(B30) humaninsulin; B29-N-palmitoyl-des(B30) human insulin; B29-N-myristoyl humaninsulin; B29-N-palmitoyl human insulin; B28-N-myristoyl LysB28ProB29human insulin; B28-N-palmitoyl-LysB28ProB29 human insulin;B30-N-myristoyl-ThrB29LysB30 human insulin; B30-N-palmitoyl-ThrB29LysB30human insulin; B29-N—(N-palmitoyl-Y-glutamyl)-des(B30) human insulin;B29-N—(N-lithocholyl-Y-glutamyl)-des(B30) human insulin;B29-N-(ω-carboxyheptadecanoyl)-des(B30) human insulin andB29-N-(ω-carboxyheptadecanoyl) human insulin.

Exendin-4 for example means Exendin-4(1-39), a peptide of the sequenceH-His-Gly-Glu-Gly-Thr-Phe-Thr-Ser-Asp-Leu-Ser-Lys-Gln-Met-Glu-Glu-Glu-Ala-Val-Arg-Leu-Phe-Ile-Glu-Trp-Leu-Lys-Asn-Gly-Gly-Pro-Ser-Ser-Gly-Ala-Pro-Pro-Pro-Ser-NH2.

Exendin-4 derivatives are for example selected from the following listof compounds:

H-(Lys)4-des Pro36, des Pro37 Exendin-4(1-39)-NH2,

H-(Lys)5-des Pro36, des Pro37 Exendin-4(1-39)-NH2,

des Pro36 Exendin-4(1-39),

des Pro36 [Asp28] Exendin-4(1-39),

des Pro36 [IsoAsp28] Exendin-4(1-39),

des Pro36 [Met(O)14, Asp28] Exendin-4(1-39),

des Pro36 [Met(O)14, IsoAsp28] Exendin-4(1-39),

des Pro36 [Trp(O2)25, Asp28] Exendin-4(1-39),

des Pro36 [Trp(O2)25, IsoAsp28] Exendin-4(1-39),

des Pro36 [Met(O)14 Trp(O2)25, Asp28] Exendin-4(1-39),

des Pro36 [Met(O)14 Trp(O2)25, IsoAsp28] Exendin-4(1-39); or

des Pro36 [Asp28] Exendin-4(1-39),

des Pro36 [IsoAsp28] Exendin-4(1-39),

des Pro36 [Met(O)14, Asp28] Exendin-4(1-39),

des Pro36 [Met(O)14, IsoAsp28] Exendin-4(1-39),

des Pro36 [Trp(O2)25, Asp28] Exendin-4(1-39),

des Pro36 [Trp(O2)25, IsoAsp28] Exendin-4(1-39),

des Pro36 [Met(O)14 Trp(02)25, Asp28] Exendin-4(1-39),

des Pro36 [Met(O)14 Trp(02)25, IsoAsp28] Exendin-4(1-39),

wherein the group -Lys6-NH2 may be bound to the C-terminus of theExendin-4 derivative;

or an Exendin-4 derivative of the sequence

des Pro36 Exendin-4(1-39)-Lys6-NH2 (AVE0010),

H-(Lys)6-des Pro36 [Asp28] Exendin-4(1-39)-Lys6-NH2,

des Asp28 Pro36, Pro37, Pro38Exendin-4(1-39)-NH2,

H-(Lys)6-des Pro36, Pro38 [Asp28] Exendin-4(1-39)-NH2,

H-Asn-(Glu)5des Pro36, Pro37, Pro38 [Asp28] Exendin-4(1-39)-NH2,

des Pro36, Pro37, Pro38 [Asp28] Exendin-4(1-39)-(Lys)6-NH2,

H-(Lys)6-des Pro36, Pro37, Pro38 [Asp28] Exendin-4(1-39)-(Lys)6-NH2,

H-Asn-(Glu)5-des Pro36, Pro37, Pro38 [Asp28] Exendin-4(1-39)-(Lys)6-NH2,

H-(Lys)6-des Pro36 [Trp(O2)25, Asp28] Exendin-4(1-39)-Lys6-NH2,

H-des Asp28 Pro36, Pro37, Pro38 [Trp(O2)25] Exendin-4(1-39)-NH2,

H-(Lys)6-des Pro36, Pro37, Pro38 [Trp(O2)25, Asp28] Exendin-4(1-39)-NH2,

H-Asn-(Glu)5-des Pro36, Pro37, Pro38 [Trp(O2)25, Asp28]Exendin-4(1-39)-NH2,

des Pro36, Pro37, Pro38 [Trp(O2)25, Asp28] Exendin-4(1-39)-(Lys)6-NH2,

H-(Lys)6-des Pro36, Pro37, Pro38 [Trp(O2)25, Asp28]Exendin-4(1-39)-(Lys)6-NH2,

H-Asn-(Glu)5-des Pro36, Pro37, Pro38 [Trp(O2)25, Asp28]Exendin-4(1-39)-(Lys)6-NH2,

H-(Lys)6-des Pro36 [Met(O)14, Asp28] Exendin-4(1-39)-Lys6-NH2,

des Met(O)14 Asp28 Pro36, Pro37, Pro38 Exendin-4(1-39)-NH2,

H-(Lys)6-des Pro36, Pro37, Pro38 [Met(O)14, Asp28] Exendin-4(1-39)-NH2,

H-Asn-(Glu)5-des Pro36, Pro37, Pro38 [Met(O)14, Asp28]Exendin-4(1-39)-NH2,

des Pro36, Pro37, Pro38 [Met(O)14, Asp28] Exendin-4(1-39)-(Lys)6-NH2,

H-(Lys)6-des Pro36, Pro37, Pro38 [Met(O)14, Asp28]Exendin-4(1-39)-(Lys)6-NH2,

H-Asn-(Glu)5 des Pro36, Pro37, Pro38 [Met(O)14, Asp28]Exendin-4(1-39)-(Lys)6-NH2,

H-Lys6-des Pro36 [Met(o)14, Trp(O2)25, Asp28] Exendin-4(1-39)-Lys6-NH2,

H-des Asp28 Pro36, Pro37, Pro38 [Met(O)14, Trp(O2)25]Exendin-4(1-39)-NH2,

H-(Lys)6-des Pro36, Pro37, Pro38 [Met(O)14, Asp28] Exendin-4(1-39)-NH2,

H-Asn-(Glu)5-des Pro36, Pro37, Pro38 [Met(O)14, Trp(O2)25, Asp28]Exendin-4(1-39)-NH2,

des Pro36, Pro37, Pro38 [Met(O)14, Trp(O2)25, Asp28]Exendin-4(1-39)-(Lys)6-NH2,

H-(Lys)6-des Pro36, Pro37, Pro38 [Met(O)14, Trp(O2)25, Asp28]Exendin-4(S1-39)-(Lys)6-NH2,

H-Asn-(Glu)5-des Pro36, Pro37, Pro38 [Met(O)14, Trp(O2)25, Asp28]Exendin-4(1-39)-(Lys)6-NH2;

or a pharmaceutically acceptable salt or solvate of any one of theafore-mentioned Exendin-4 derivative.

Hormones are for example hypophysis hormones or hypothalamus hormones orregulatory active peptides and their antagonists as listed in RoteListe, ed. 2008, Chapter 50, such as Gonadotropine (Follitropin,Lutropin, Choriongonadotropin, Menotropin), Somatropine (Somatropin),Desmopressin, Terlipressin, Gonadorelin, Triptorelin, Leuprorelin,Buserelin, Nafarelin, Goserelin.

A polysaccharide is for example a glucosaminoglycane, a hyaluronic acid,a heparin, a low molecular weight heparin or an ultra low molecularweight heparin or a derivative thereof, or a sulphated, e.g. apoly-sulphated form of the above-mentioned polysaccharides, and/or apharmaceutically acceptable salt thereof. An example of apharmaceutically acceptable salt of a poly-sulphated low molecularweight heparin is enoxaparin sodium.

Antibodies are globular plasma proteins (˜150 kDa) that are also knownas immunoglobulins which share a basic structure. As they have sugarchains added to amino acid residues, they are glycoproteins. The basicfunctional unit of each antibody is an immunoglobulin (Ig) monomer(containing only one Ig unit); secreted antibodies can also be dimericwith two Ig units as with IgA, tetrameric with four Ig units liketeleost fish IgM, or pentameric with five Ig units, like mammalian IgM.

The Ig monomer is a “Y”-shaped molecule that consists of fourpolypeptide chains; two identical heavy chains and two identical lightchains connected by disulfide bonds between cysteine residues. Eachheavy chain is about 440 amino acids long; each light chain is about 220amino acids long. Heavy and light chains each contain intrachaindisulfide bonds which stabilize their folding. Each chain is composed ofstructural domains called Ig domains. These domains contain about 70-110amino acids and are classified into different categories (for example,variable or V, and constant or C) according to their size and function.They have a characteristic immunoglobulin fold in which two β sheetscreate a “sandwich” shape, held together by interactions betweenconserved cysteines and other charged amino acids.

There are five types of mammalian Ig heavy chain denoted by α, δ, ε, γ,and μ. The type of heavy chain present defines the isotype of antibody;these chains are found in IgA, IgD, IgE, IgG, and IgM antibodies,respectively.

Distinct heavy chains differ in size and composition; α and γ containapproximately 450 amino acids and δ approximately 500 amino acids, whileμ and ε have approximately 550 amino acids. Each heavy chain has tworegions, the constant region (C_(H)) and the variable region (V_(H)). Inone species, the constant region is essentially identical in allantibodies of the same isotype, but differs in antibodies of differentisotypes. Heavy chains γ, α and δ have a constant region composed ofthree tandem Ig domains, and a hinge region for added flexibility; heavychains μ and ε have a constant region composed of four immunoglobulindomains. The variable region of the heavy chain differs in antibodiesproduced by different B cells, but is the same for all antibodiesproduced by a single B cell or B cell clone. The variable region of eachheavy chain is approximately 110 amino acids long and is composed of asingle Ig domain.

In mammals, there are two types of immunoglobulin light chain denoted byλ and κ. A light chain has two successive domains: one constant domain(CL) and one variable domain (VL). The approximate length of a lightchain is 211 to 217 amino acids. Each antibody contains two light chainsthat are always identical; only one type of light chain, κ or λ, ispresent per antibody in mammals.

Although the general structure of all antibodies is very similar, theunique property of a given antibody is determined by the variable (V)regions, as detailed above. More specifically, variable loops, threeeach the light (VL) and three on the heavy (VH) chain, are responsiblefor binding to the antigen, i.e. for its antigen specificity. Theseloops are referred to as the Complementarity Determining Regions (CDRs).Because CDRs from both VH and VL domains contribute to theantigen-binding site, it is the combination of the heavy and the lightchains, and not either alone, that determines the final antigenspecificity.

An “antibody fragment” contains at least one antigen binding fragment asdefined above, and exhibits essentially the same function andspecificity as the complete antibody of which the fragment is derivedfrom. Limited proteolytic digestion with papain cleaves the Ig prototypeinto three fragments. Two identical amino terminal fragments, eachcontaining one entire L chain and about half an H chain, are the antigenbinding fragments (Fab). The third fragment, similar in size butcontaining the carboxyl terminal half of both heavy chains with theirinterchain disulfide bond, is the crystalizable fragment (Fc). The Fccontains carbohydrates, complement-binding, and FcR-binding sites.Limited pepsin digestion yields a single F(ab′)2 fragment containingboth Fab pieces and the hinge region, including the H—H interchaindisulfide bond. F(ab′)2 is divalent for antigen binding. The disulfidebond of F(ab′)2 may be cleaved in order to obtain Fab′. Moreover, thevariable regions of the heavy and light chains can be fused together toform a single chain variable fragment (scFv).

Pharmaceutically acceptable salts are for example acid addition saltsand basic salts. Acid addition salts are e.g. HCl or HBr salts. Basicsalts are e.g. salts having a cation selected from alkali or alkaline,e.g. Na+, or K+, or Ca2+, or an ammonium ion N+(R1)(R2)(R3)(R4), whereinR1 to R4 independently of each other mean: hydrogen, an optionallysubstituted C1-C6-alkyl group, an optionally substituted C2-C6-alkenylgroup, an optionally substituted C6-C10-aryl group, or an optionallysubstituted C6-C10-heteroaryl group. Further examples ofpharmaceutically acceptable salts are described in “Remington'sPharmaceutical Sciences” 17. ed. Alfonso R. Gennaro (Ed.), MarkPublishing Company, Easton, Pa., U.S.A., 1985 and in Encyclopedia ofPharmaceutical Technology.

Pharmaceutically acceptable solvates are for example hydrates.

It will be further apparent to those skilled in the pertinent art thatvarious modifications and variations can be made to the presentinvention without departing from the spirit and scope of the invention.Further, it is to be noted, that any reference signs used in theappended claims are not to be construed as limiting the scope of thepresent invention.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following, an embodiment of the invention will be described bymaking reference to the drawings, in which:

FIG. 1 schematically shows a first embodiment of a drive mechanismcomprising an accessory drive,

FIG. 2 shows another embodiment of the drive mechanism,

FIG. 3 is indicative of a switch implemented in the dosing arrangementin a first configuration,

FIG. 4 shows the switch in a second configuration,

FIG. 5 shows another embodiment of a switch in a first configuration,

FIG. 6 shows the switch according to FIG. 5 in a second configuration,

FIG. 7 is indicative of a proximal portion of the housing comprising aconductor path,

FIG. 8 shows another embodiment of the switch in a first configuration,

FIG. 9 is indicative of a second configuration of the switch accordingto FIG. 8,

FIG. 10 shows another embodiment of a switch in a first configurationand

FIG. 11 shows another, second configuration of the switch according toFIG. 10.

DETAILED DESCRIPTION

FIGS. 1 and 2 illustrate two different embodiments of an accessory drive26 integrated in a drive mechanism 3 of a drug delivery device 10. Asillustrated in FIGS. 1 and 2, the drug delivery device 10 and hence thedrive mechanism 3 comprise a housing 12 to accommodate a cartridge 14filled with a medicament to be dispensed by the drive mechanism 3. Thecartridge 14 comprises a distally located seal 16, typically featuring apiercable septum to be penetrated by a double-tipped injection needle,which is not particularly illustrated here.

The cartridge 14 comprises a tubular-shaped barrel 18 which is sealed inproximal direction 2 by way of an axially displaceable piston 20. Thedrive mechanism 3 comprises at least a piston rod 22 to operably engagewith the piston 20 of the cartridge 18. During a dispensing procedure,the piston rod 22 advances in distal direction 1 in order to exertpressure or thrust to the piston 20 for driving and advancing the samein distal direction 1. This way, a predefined amount of the medicamentcontained in the cartridge 14 can be expelled via the injection needlepenetrating the proximal seal 16 of the cartridge 18.

The drive mechanism 3 comprises an accessory drive 26 electricallyconnected with a battery 24. The power operated accessory drive 26 iscontrollable via a control 44, by way of which the accessory drive 26can be selectively activated or deactivated for supporting a dosedispensing procedure to be conducted by the drive mechanism 3. Theaccessory drive 26 is provided with a drive member or drive shaft 28,which, in the embodiment according to FIG. 1 is operably and directlyengaged with a gear wheel 30 located on a dose indicating member 32 of adosing arrangement 31 of the drive mechanism. The dose indicating member32 comprises a dose indicating sleeve 32 featuring a series of numbersprinted on its outer circumference, for indicating the size of a doseactually set by the dosing arrangement 31.

The dosing arrangement 31 comprises the sleeve-like dose indicatingmember 32 and a dose setting member 34, which may be implemented as adose dial grip allowing a user to rotate the dose setting member 34 andthe dose indicating member 32 in a screw-like motion for displacing thedosing arrangement 31 in proximal direction 2 relative to the housing12, in particular for setting of a dose.

At its proximal end the dosing arrangement 31 comprises a dosedispensing member 36 which may be implemented as a dose button toreceive a distally-directed dispensing force 42 exerted by e.g. a thumbof a user. During a dose dispensing procedure, the dosing arrangement 31may return into an initial configuration. A correspondingdistally-directed and user activated displacement of the entire dosingarrangement 31 relative to the housing 12 may come along with arespective counter-directed rotation of the dose indicating member 32and/or of the dose setting member 34.

Typically, the drive mechanism 3 comprises a clutch mechanism 38,indicated in FIGS. 1 and 2, by way of which the drive mechanism 3 can beswitched from the dose setting mode into the dose dispensing mode andvice versa. The clutch mechanism 38 is typically activated by depressingthe dose button or dose dispensing member 36 in distal direction 1 atthe beginning of a dose dispensing procedure.

The clutch 38 may be implemented in the dosing arrangement 31. It mayprovide an axially directed displacement between the dose setting member34 and/or the dose dispensing member 36 relative to the dose indicatingmember 32, against the action of a spring force provided by a springelement.

In the interface between the dose dispensing member 36 and the dosesetting member 34 or in the interface between the dose dispensing member36 and the dose indicating member 32 a switch 40 is integrated as willbe explained in greater detail with respect to FIGS. 3-11.

The switch 40 is electrically connected to the accessory drive 26, inparticular to its control 44. Activation or deactivation of the switch40 during a dose dispensing procedure will typically activate anddeactivate the accessory drive 26 in order to support a dispensingaction of the drive mechanism 3. As illustrated in FIG. 1, applicationof a distally-directed dispensing force 42, which is provided by a userof the device 10 may close or open the switch 40, thereby activating theaccessory drive 26.

Under the action of both, the torque provided by the accessory drive 26and by the force 42 provided by the user, the dosing arrangement 31 isoperable to return into its initial configuration while applying adistally-directed advancing motion to the piston rod 22.

The accessory drive 26 may be dimensioned such that the torque to beprovided via the drive member 28 is generally sufficient to move thepiston rod 22 in distal direction 1. For dispensing of a dose it may betherefore sufficient just to apply a dispensing force 42 which is largeenough to activate the switch 40 at the proximal end of the dosingarrangement 31.

Typically, the switch 40 is spring biased so that a premature release ofthe dose dispensing member 36 during a dose dispensing procedureimmediately returns the switch 40 into an initial non-biasedconfiguration, which is correlated with a deactivated accessory drive26. As a consequence, release of the dose dispensing member 36 can beimmediately transferred to a respective stop of the accessory drive.

In this way, the electrically- and/or power supported accessory drive 26of the mechanism 3 provides a look and feel of an all-mechanicallyimplemented drive mechanism 3. However, by means of the accessory drive26, the magnitude of a dispensing force 42 required to trigger or toconduct a dispensing procedure can be effectively and advantageouslyreduced.

In the embodiment according to FIG. 1, the accessory drive 26 isdirectly engaged with the dose indicating member 32, e.g. in form of adose sleeve of the drive mechanism 3. In this way, mechanical powerprovided by the accessory drive 26 is transferred to the piston rod 22via the dose indicating member 32. In this embodiment, dose indicatingmember 32 and piston rod 22 remain coupled also during or for a dosedispensing procedure. Consequently, the axial position of the doseindicating member 32 is strictly correlated to the axial and actualposition of the piston rod 22. By way of the mutual engagement of thedose indicating member 32 with the piston rod 22 the dose indicatingmember 32 always reflects the size of a dose actually dispensed by thedrive mechanism 3.

In the embodiment according to FIG. 2, the accessory drive 26 isoperably engaged with the piston rod 22. Hence, the gear wheel 30 thatmeshes measures with the drive member 28 of the accessory drive 26 isdirectly engaged with the piston rod 22. Here and in contrast to theembodiment according to FIG. 1, activation of the accessory drive 26during a dose dispensing procedure may be without any effect to theconfiguration of the dosing arrangement 31.

Torque- or mechanical energy transmission between the accessory drive 26and the piston rod 22 can be implemented in a rather direct way.Depending on the type of clutch mechanism 38 implemented between thedosing arrangement 31 and the piston rod 22 it is also conceivable withthe embodiment according to FIG. 2, that the distally-directed andaccessory drive supported displacement of the piston rod 22 is equallytransferred to a corresponding distally directed displacement of theentire dosing arrangement 31.

The switch 40 as will be explained and illustrated in FIGS. 3-11 mayfeature a binary on/off functionality for activating or deactivating theaccessory drive 26. In an alternative or additional embodiment it isalso conceivable, that the switch 40 is implemented as a kind of a loadcell or on the basis of at least one pressure sensitive member allowingto measure or to determine the magnitude of a force 42 exerted by a userof the device.

In this way, the power or driving force of the accessory drive 26 can beregulated accordingly. Here, the power of the accessory drive 26 can beindividually and instantaneously adapted to the force 42 applied by auser for dose dispensing.

The cross-sectional illustration of FIG. 3 shows a proximal end of thedosing arrangement 31 during or after setting of a dose. For setting ofa dose, the dose setting member 34 in form of a dose dial is to berotated. As illustrated in FIG. 3, there are provided two radiallyinwardly extending spring-biased contact members 50, 51 at the innercircumference of the dose indicating member 32. In the configurationaccording to FIG. 3 the contact members 50, 51 are in mechanical contactwith a circumferentially extending conductive ring 52 provided on anouter circumference of the dose setting member 34. By means of theconductive ring 52 an electrical contact between the oppositely locatedcontact members 50, 51 can be established.

In the present embodiment, two contact members 50, 51 will deactivatethe accessory drive 26 when in electrical contact with the conductivering 52. Moreover, the dose setting member 34 and the dose dispensingmember 36 are integrally formed. Hence, the dose dispensing member 36forms a proximal end face of the dose dial or dose setting member 34.

Application of a distally-directed dispensing force 42 onto the dosesetting member 34 or dose dispensing member 36 displaces the dosesetting member 34 relative to the dose indicating member 32, whichcarries the two oppositely disposed contact members 50, 51. Since theconductive ring 52 is assembled to the dose setting member 34, theconductive ring 52 is axially and distally displaced relative to the twocontact members 50, 51, thereby interrupting the electrical contactbetween the two contact members 50, 51.

Electrically disconnecting the two contact members 50, 51 then activatesthe accessory drive 26 via the control 44. At the same time, therelative axial displacement of dose setting member 34 and doseindicating member activates or deactivates the clutch, therebymechanically switching the drive mechanism 3 into a dose dispensingmode.

The distally-directed displacement of the dose setting member 34relative to the dose indicating member 32 and/or relative to the housing12 typically occurs against the action of a spring, which is notexplicitly illustrated here. As soon as the externally applieddispensing force 42 drops below a predefined threshold, said spring willserve to return the dose setting member 34 into its initialconfiguration as shown in FIG. 3, thereby closing the contact betweenthe contact members 50, 51. As a consequence, the accessory drive 26will then be deactivated.

In another embodiment according to FIGS. 5-7, the switch 40 isimplemented as a conductive ring 52 located at an inside wall portion ofthe dose setting member 34. As shown in FIGS. 5-7, the dose indicatingmember 32 in form of a dose indicating sleeve comprises radiallyoutwardly extending and diametrically oppositely located protrusions 56at a proximal end. The protrusions 56 are provided with conductor paths46 extending in axial direction along the sleeve-like dose indicatingmember 32.

Also here, distally-directed displacement of the dose setting member 34relative to the dose indicating member 32 against the action of arestoring spring brings the contact members 50, 51 out of engagementwith the conductive ring 52. Consequently, and as already described inconnection with the embodiment according to FIGS. 3 and 4, saiddisconnection may come along with an activation of the accessory drive26.

In FIGS. 8 and 9 another embodiment is schematically illustrated,wherein the circumferentially extending conductive ring 52 is locatedand arranged on an inner sleeve portion 58 of the dose setting member 34while oppositely located contact members 50, 51 are assembled andarranged at the proximal end of the dose indicating member 32. Here, thecontact members 50, 51 are biased radially inwardly to mechanicallyengage with the conductive ring 52. As becomes apparent from acomparison of FIGS. 8 and 9, a distally-directed displacement of thedose setting member 34 relative to the dose indicating member 32 leadsto an electrical disconnection of the two contact members 50, 51 withthe same or with a similar effect on the accessory drive 26 as alreadyexplained above.

In still another embodiment, as shown in FIGS. 10 and 11, the conductivering 52 is supported on an inside facing wall portion of the dosesetting member 34 or dose dispensing member 36 while the contact members50, 51 are biased radially outwardly by means of a radially outwardlyextending protrusion 56 located on the inner sleeve portion 58 of thedose setting member 34. Also here, axially-directed displacement of thedose setting member 34 and hence of the radially outwardly extendingprotrusion 56 allows that the contact member 50 is displaced radiallyinwardly, thereby releasing from the conductive ring 52 as shown in FIG.11.

Even though the embodiment according to FIGS. 10 and 11 is illustratedwith only one contact member 50 it may be equally implemented with twodiametrically oppositely disposed contact members 50, 51 as illustratedand explained with regard to FIGS. 3-9.

In another implementation the contact members 50, 51 may be coupled tothe control 44 and/or to the accessory drive 26 in a different way sothat only establishing of an electrical interconnection of the contactmembers 50, 51 leads to an activation of the accessory drive 26 in thedispensing mode of the drive mechanism 3. Accordingly, disconnecting ofthe contact members 50, 51 may then come along with a deactivation ofthe accessory drive 26.

The invention claimed is:
 1. A drive mechanism of a drug delivery devicefor setting and dispensing of a dose of a medicament, the drivemechanism comprising an elongated housing extending in an axialdirection, a piston rod to operably engage with a piston of a cartridgecontaining the medicament, a dosing arrangement manually and axiallydisplaceable relative to the housing for setting and dispensing of thedose, and comprising a dose dispensing member at a proximal end, anaccessory drive operably engaged with the piston rod to support amanually operated distally directed dose dispensing displacement of thedosing arrangement, wherein the accessory drive is electrically driven,and wherein the accessory drive is further coupled with a switch toselectively activate and/or deactivate the accessory drive, and whereinthe switch is operably engaged with the dose dispensing member.
 2. Thedrive mechanism according to claim 1, wherein the dosing arrangementcomprises a dose setting member, a dose indicating member and the dosedispensing member.
 3. The drive mechanism according to claim 2, whereinthe accessory drive is operably engageable with the dose setting memberor with the dose indicating member during a dose dispensing procedurefor dispensing of the dose.
 4. The drive mechanism according to claim 3,wherein the dose indicating member is operably engaged with the pistonrod during dose dispensing.
 5. The drive mechanism according to claim 2,wherein the dose dispensing member is operably engaged with the pistonrod during dose dispensing.
 6. The drive mechanism according to claim 1,wherein the dosing arrangement is axially displaceable in proximaldirection relative to the housing for setting of the dose.
 7. The drivemechanism according to claim 1, wherein the switch is located in aninterface between the dose dispensing member and the dose setting memberand/or the dose indicating member.
 8. The drive mechanism according toclaim 1, wherein the switch is actuatable against a restoring force. 9.The drive mechanism according to claim 1, wherein the switch is operableto quantitatively determine a dispensing force acting thereon in distaldirection during dose dispensing.
 10. The drive mechanism according toclaim 1, further comprising a control to regulate the power of theaccessory drive in dependence of an applied dispensing force.
 11. A drugdelivery device for setting and dispensing of a dose of a medicament,the device comprising a drive mechanism according to claim 1 and acartridge operably engaged with the piston rod of the drive mechanism.